Micromagnetic Simulation of Mo-Multilayers

Abstract

~ Micromagnetic finite element calculations rigorously describe the effects of microstructural features on the magnetic properties of ColPt multilayer thin films. Within the framework of static micromagnetism. the hysteresis properties result from subsequent minimum energy solutions for decreasing or increasing applied fields. The concurrent modelling of inhomogeneous magnetic states within the individual grains and of co-operative reversal processes leads to a large-scale optimisation problem. In order to reduce the number of variables. shell elements which account for the multilayer structure and a magnetic vector potential to treat the long-range stray fields are used. Micromagnetic calculations of demagnetisation curves and domain structures in ColPt multilayer systems show a qualitative agreement with experimental data obtained from Lorentz electron microscopy. The nucleation field of ColPt multilayer increases with improving texture. Spatial fluctuations of the anisotropy directions from grain to grain create barriers for domain wall . motion. The pinning field increases with increasing grain size. The coercive squareness improves with decreasing number ofbilayers. The ac-demagneJised state shows a maze-like structure. The underlying skeleton shape of the domain structure remains substantially unchanged under an applied field. The transition width and the domain wall jaggedness increase with decreasing quality of texture and increasing grain size.

Exchange spring behaviour in SrFe12O19-CoFe2O4 nanocomposites

“…[1][2][3][4][5][6][7][8] The proposition for exchange spring concept has been attributed to Knellers and Hawig. 9 They proposed an enhancement in content of transition metal in permanent magnets by making a nanocomposite comprising exchange-coupled hard and soft magnetic phases.…”

Multimode switching induced by a transverse field in planar magnetic nanowires

“…At one end of each nanowire, a larger rectangular nucleation pad of Permalloy was fabricated. The other end was pointed to suppress domain wall nucleation 13 and resultant domain wall motion from this end. The four L-shaped wires studied had widths of 184 nm, 303 nm, 321 nm, and 537 nm, as measured by scanning electron microscopy ͑SEM͒.…”

The effects of the thickness of magnetically hard- and soft-phase layers on magnetic properties and exchange coupling in multilayer magnets

“…1 Taking advantage of a high coercivity and a high magnetization provided by the hard-and the soft-magnetic components, respectively, a high remanence and a large maximum energy product would be obtained if a full and perfect exchange coupling existed between the grains of the two phases in nanocomposite magnets, as predicted by micromagnetic calculations. [2][3][4] However, up to now, the energy products of the rare-earth nanocomposite magnets prepared by means of rapid quenching and mechanical alloying have been much lower than the theoretical expectation, due to difficulties in controlling the nanostructures. [5][6][7][8] Recently, some studies on exchange coupling were carried out for nanostructured CoSm/ FeCo and PrCo/ Co multilayers prepared by sputtering and subsequent heat treatment.…”